How much time does it take to bicycle the street network in each grid polygon?

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07-20-2016 02:00 PM
AnneWynn
New Contributor II

We are creating a mapping project using data driven pages in order to easily print out individual pages for specific geographic areas as the need arises.  Each page will be an individual grid cell of a polygon grid network that I've created to overlay the entire city street GIS network.  How can I determine how long it would take a bicyclist (on average) to ride all streets in each grid cell?  Do I have to create a To-From route event table and manually select lines and points in each grid cell to do this?

Any insight on this problem is greatly appreciated,

Anne W.

I Bike Tuscaloosa (Bicycle Safety Awareness Community Organization)

7 Replies
DarrenWiens2
MVP Honored Contributor

What data do you have to work with? For example, are the streets attributed with speed (e.g. 20mph) or time (e.g. 0.05 hours/mile)? Or do you have a completely blank street file?

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AnneWynn
New Contributor II

The file I have is a tiger line street file, as is. It has street type listed in the attribute table.  Would it help if I add a field for mph to the attribute table?  But since this is for cyclists instead of cars, would mph be helpful to add to the attribute table?

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DarrenWiens2
MVP Honored Contributor

Maybe I'm thinking about this the wrong way, but I don't see this as a network problem at all. If you attribute your lines with bike speed or time, you can then intersect it with your grid to get the total length of each line type, multiply the length by the speed or time to get the total per line type within the grid cell, then add those all up to get the grid cell total.

So, say you've got 2 miles of primary road and 10 miles of secondary road in a grid cell. You decide that you can bike 20mph on primary and 10mph secondary. 20mph = 0.05h/mile, 10mph = 0.1h/mile. 2 * 0.05 = 0.1h on primary, 10 * 0.1 = 1h on secondary. Total time = 1.1h or 66 minutes.

edit: OR are you trying to determine how long it would take a cyclist to physically visit each street, possibly including time outside the grid cell?

AnneWynn
New Contributor II

That is a great idea!!

I think one network problem for cyclists would be contending with busy intersections with heavy traffic flow.

And yes, I am trying to determine how long it would take to physically maneuver through the street network in each grid cell.  We want to just focus on each grid cell as a separate unit.

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DanPatterson_Retired
MVP Emeritus

You must be treating the roads within the grids as discrete entities, since you are going to have to rule out duplicate path traversal... that is,you do not have specific origins and destinations.

AnneWynn
New Contributor II

Good point, Dan!  Roads with no outlet would need to be counted twice, since the bicyclist would have to go back the way they came in.  Hmmm......... Should I create a network dataset from my road layer and create a route, using my grid as a polygon barrier in the route?  I am just learning how to use network analysis tools - forgive me!

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DanPatterson_Retired
MVP Emeritus

No... I am suggesting a design question which hasn't been addressed.  You indicate/suggest traversal through the blocks, which means you are going from A to B, neither of which need be in the block.  If you simply leave that out of the question, then you simply want the weighted sum of the roads within the block.  It becomes irrelavent about the mode of transport, except in how you weight the road segments.  Turns as well... who says the cyclist has to turn?

So if you are looking at 'going to a destination' then you need to identify these origins and destinations, or more simply just select your routes knowing full well that other road segments will never be 'visited' by the chosen mode of transportation.  Cycle routes would be such a case.  You know the routes, their properties so effectively you have all the data in segmented form.  Just cut it into bits and summarize for you blocks.  There is no need to use the Network Analyst or anything else.  Network Analyst is not the best use tool to answer the ... 'I know where I am going... and I know how I am going to get there...' questions

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